Rotary piston pump



Dec. 22, 1964 F. THOMPSON 3,

ROTARY'PISTON PUMP Filed May 20, 1963 4 Shets-Sheet 1 l8 lI l5 45 46 l9 I2G\ H T II I INVENTOR. Theodore E Thompson ATTORNEYS 22, 1964 T. F. THOMPSON 3,

ROTARY PISTON PUMP Filed May 20, 1963 4 Sheets-Sheet 2 INVENTOR. Theodore E Thompson ATTORNEYS 1954 T. F. THOMPSON 3,132,139

ROTARY PISTON PUMP Filed May 20, 1963 4 Sheets-Sheet 4 INVENTOR. Theodore E Thompson ATTORNEYS United States "Patent Colo.

Filed May 20, 1963, Ser. No. 281,420 4 Claims. (Cl. 103-130) This invention relates to rotary piston pumps and more particularly to pumps including at least two co-acting rotary pistons which are interconnected to a novel valve arrangement and which the rotary pistons are driven by conjugant gears.

Rotary piston pumps, particularly where two rotary pistons are used in a single housing are known in the art, however, there are certain inherent disadvantages in the rotary piston pumps where the pistons are in contact with one another and rotate while in contact with one another. The valving of the pump to provide a closure between the inlet and outlet of the pump is difiicult due to the geometry of the system, particularly where the rotary pistons are eccentrically mounted in cylindrical chambers. The inlet and outlet must, of course, be separated so as to provide a means for producing a suction and a pressure. Additionally, where the pistons operate in contact with each other considerable wear has been experienced due to the sliding contact with either the pitsons against each other or the pistons again-st the wall. In the pumps which do not have contact between the rotary pistons and/ or the walls, the pressure attain-able is limited.

It is an object of the invention to provide a pump utilizing at least two rotary pistons for providing suction and pressure with reduced wear and high efiiciency. The pump of the invention provides a simple construction utilizing a highly efiicient and simple valve for forming a closure between the inlet and the outlet of. a rotary piston pump. The invention provides means for the efiicient use of resilient rotors where desred, and provides means to utilize the rotors in multiple sets of two, which pumps may have four or more rotors for high efficiency and high volume while maintaining the pump size and weight at a minimum.

These and other objects and advantages of the invention may be readily ascertained by referring to the following description and appended illustrations, in which FIG. 1 is a side elevational view of one form of th pump according to the invention;

FIG. 2 is a cross-sectional view of the pump of FIG. 1 taken along section line 2-2;

FIG. 3 is a top plan view of a valve element according to the invention;

FIG. 4 is a side elevational view of the slide of the valve section of FIG. 3 taken along section lines 44;

FIG. 5 is a side elevational view, partially cut away, of a pump, according to the invention, in one position illustrating the operation of the pump and the slide;

FIG. 6 is a similar view to FIG. 5 illustrating a subsequent position of the rotary pistons of the pump;

FIG. 7 is a similar View to FIG. 5 showing a still further position of the rotary pistons of the invention during operation thereof;

FIG. 8 is a top plan view of a four rotor pump according to the invention;

FIG. 9 is an end elevation of a four rotor pump according to the invention illustrating the mounting of a driv motor thereon;

FIG. 10 is a top plan view of a two rotor pump according to the invention;

FIG. 11 is a side elevation of a pump according to the invention showing a modified valve;

FIG. 12 is a top plan view of a valve slide according to the invention;

FIG. 13 is a cross-sectional view of the slide of FIG. 12 taken along section lines 13-13; and

FIG. 14 is a schematic view of one form of rotary piston according to the invention.

In general, one form of the pump of the invention is provided with a housing which has two substantially identical cylindrical chambers interconnected by a passage.

The passage intersects each chamber along a line passing through both centers of the chambers, however, the passage is substantially smaller than the diameter of the chambers. A rotary piston, of a diameter smaller than the diameter of the chamber, is eccentrically mounted in each chamber. A slideatype valve is arranged in the passageway between the cylinders of such a size to contact each of the rotors when the rotors are arranged to rotate conjo-intly but oppositely in the chambers. The rotors are arranged on their shafts so as to maintain a uniform distance apart during their rotation. The two rotary pistons are geared together so as to conjlointly rotate at the same speed and in the opposite direction. A resilient covering for each of the rotary pistons is rotatably mounted on the eccentric so that the covering of the piston does not slide on the wall of the chamber.

In the two rotor pump shown in FIGS. 1 and 2 a main body 10 is provided with end members 11 and 12 generally closing hollow cylindrical chambers 15 and 16 in the housing 10. A shaft 18 is journalled in end member 12 (not shown) journalled through the end plate 11 and into an outside plate 19, the journalling being by a packing box to prevent leaking and provide free rotation of the shaft. The end plate 12 is secured to the housing by means of bolts or cap screws 20 holding a gasket plate 21 therebetween. In a similar manner the outside plate 19 and the end plate 11 are secured to the housing 11) by means of cap screws or bolts 24 maintaining a gasket plate 26 between the body 10 and the end plate 11. The shaft 18 passes through the housing and outside the end plate 11 there is mounted a gear 27. This gear 27 mates with gear 28 onshaft 29 in the opposite cylinder and provides means for interconnecting the rotors of the pump. The pump is provided with an inlet 30 near its bottom and an outlet 31 at its top. Both the inlet and the outlet have threaded portions to accommodate lines which may extend through openings in the back plate 19 to the threaded portion. A passage 33 is provided between the cylindrical chambers 15 and 16 and a slide valve 35 is mounted therein, the slide valve being described in detail below. Inlet 30 is connected to passage 33 by a connecting passage 30a, and the outlet 31 is connected by a connecting passage 31a to the passage 33. The end plate 12 is provided with feet 12a and the back plate 19 is provided with feet 1% for supporting the pump on a base.

The rotary piston for each cylinder is shown in detail in FIG. 14 wherein a shaft 36 has fixedly mounted thereon an eccentric 37, and a resilient covering 38 is rotatably mounted on the roller bearing set 39 (not completely shown). In one form, a metal tube is secured to the flexible covering 38 and the bearing set is rotatably mounted between it and the eccentric 37. The covering 38 is preferably a tough, resilient plastic or synthetic resin such as Teflon which is a brand of a fluorohydrocarbon polymer, other types of fiuorohydrocarbons may be equally useful under some conditions as well as other resins such as polypropylenes and the like under other conditions.

The slide valve shown in FIGS. 3 and 4 comprises a upper elongated recesses 41 and 42.

with the slide bearing against both rotors.

The valve 46 is, "additionally, provided with a single recess 43 in the lower side beneath the two upper cutouts and a series of small depressions 44 in the single cutout are arranged to support the slide valve on ball bearings 45, shown in dash lines in FIG. 4. A bearing plate 46, shown in FIG. 2, is arranged to support the ball bearings in their movement in the valve area. Thevalve slide is made of a resilient, tough plastic or synthetic resin and it is arranged to bearagainst the flexible covering of the cylindrical pistons. The valve slide is shaped to alternately open both the inlet and outlet of one cylinder while the other is closed to both inlet and outlet and then close the inlet and outlet of the first cylinder while opening the inlet and outlet of the second, with a repetitious action. The slide bears against each piston so there is a seal between the inlet and outlet of each cylinder whether opened or closed. 1

One'sequence of the operation is shown in FIGS. 5, 6, and 7 where, in FIG. 5, both rotors are to the far right The flow of fluid is indicated by the arrows showing the lower space of each chamber opens to the inlet and the upper space of each chamber opens to the outlet. In FIG. 5 position, the right hand chamber 16 is open to the inlet and the outlet 31, while the left chamber 15 is completely closed from either inlet or outlet. Note the slide seals the inlet from the outlet. In FIG. 6 a quarter of a revolution later both chambers areclosed. In FIG. 7, which is 180 from FIG. 5 and 90 from FIG. 6, the lefthand chamber 15 is fully open to both the inlet and outlet and the righthand chamber 16 is fully closed to the inlet orthe outlet. The sequence continues on around through the next 180 in a similar manner with an opposite result of each of the cylinders. The motion of the rotor produces a suction on the inlet to draw fluid in, and continued rotation forces thefiuid out the outlet. The action is an increasing volume to produce suction and a decreasing volume to produce pressure. 7

A compound pump having four pistons is illustrated in FIGS; 8 and 9, wherein a pair of piston housings 6i and n1 is connected together with a gasket 62 therebetween. An end plate s3 is secured to the housing 61 closing the openings therein and a gasket 64 provides a seal. On the opposite side of housing an end plate 65 with a seal 66 is secured to complete the pump housing by bolts, cap screws, etc. The housing 60 has a pair of circular cylinders 67 and 68 therein and the housing 61 has a pair of cylindrical chambers 69 and 70 therein. A shaft 71 mountedin the chambers has a pair of pistons 73 and 74 mounted on eccentrics 77 and 78 on the shaft. The outer end of the shaft 7t? is jcurnaled in bearing member while the opposite end is journaled in bearing member 76. The opposed eccentrics 77 and '78 are milled or otherwise securedto the shaft, properly spacing the pistons 73 and 74 in the chambers 67 and 69. A gear 7h is mounted on the outer end of the shaft 71. In a similar manner, a shaft 80 with a pair of eccentrics 81 and 82 has mounted thereon rotary pistons 83 and 84, respectively. The pistons 83 and 84 are mounted'in chambers 68 and 76, respectively. One end of the shaft 89 is mounted in bearing assembly 85 and the opposite end is mounted in bearing assembly 86. A gear 87 is mounted on the shaft 81 and it meshes with the gear 79 so that the two shafts rotate concurrently. The gears are enclosed in a housing 93 at the front end secured by cap screws or the like. A cover 89 encloses the opposite end of the shaft and cap screws 90 are arranged to hold the cover in place. In similar manner, a cover 91 is held by cap screws 2 covering the rear end of the shaft 80.

A slide valve MI is mounted between the pistons 73 and 83 and a slide valve 95 is mounted between the pistons 69 and 84. The valves are mounted in a manner similar to that shown in FIGS. 1-7, and both operate similarly. The shaft 89 is sealed by means of an O-ring 9S, and the shaft 71 is sealed likewise with an O-ring 96. The pump parts are held together by such means as cap screws, bolts, and the like in the usual manner.

A motor gear reducer assembly 1% having a reducing gear box 101 is attached to a small gear Hi3 mounted on a shaft 134 which is connected to the gear reducer Till. The gear 193 is connected with the gears 79 and 37 for driving the pump.

An inlet pipe Hi5 is connected with an inlet manifold opening 1% which extends in both housings and communicates with the slide valves W; and E5. The slots in the slide valves provide means'for passing fluid into the pump on the intake strokes. An outlet 107 connected with an outlet manifold passage 168 which extends into both housings and communicates with the slide valves in a manner similar to that of the single slide shown in F168. l7 provides an outlet for the fluid. The inlet and outlet manifolds are common passages to both sets of cylinders, whereby fluid enters and is exhausted from the side by side cylinders alternately, providing in effect 4 strokes for each revolution of the shafts.

A modified pump, illustrated in FIGS. 16 and 11, includes a housing 11d provided with cylinders in and 112 with a shaft 112 mounted in the cylinder 111 and a shaft 113 mounted in the chamber 112. An eccentric 114 is mounted on a shaft 112 and an eccentric 115 is mounted on the shaft 113. A piston 11!: is mounted on the eccentric 114- and a piston 117 is mounted on er.- centric 115. The housing is closed at one side by means of a plate 118 and by a plate 119 on the opposite side. Shaft 112 is journaled in bearing means 120 at one end and in bearing assembly 121 at the opposite end. A cap 122. encloses the end of the shaft 112 and a cap 123 encloses the end of the shaft 113. A gear 125 is attached to the shaft 126 and the gear 112 is, likewise, attached to the shaft 113 and the shafts are inter-meshed on conjoint rotation. An G-ring seal I27 seals the shaft 112 and O-ring 128 seals shaft 113.

'A slide 131 is mounted between the two pistons and is arranged in contact with each of the pistons. Each end of the slide has a triangular shape (in cross section) projection 13 and 132. The piston 116 has a triangular indent 133 which is arranged to mate with the projection 132 and the piston 117 has a triangular indent 134 which mates with the projection 132. Ball bearings 135 provide bearing means for the slide.

The pump shown in FIGS. 10 and 11 operates in a manner similar to the other pumps except that the slide with the projections in register with the grooves in the pistons prevents the pistons from rotating. The pistons move in their eccentric arc in the chambers and the movement forces the slide back and forth, opening and closing the inlets and outlets in a manner similar to that described in the pump, FIG. 1. The projections in their mating grooves keep a positive seal and prevent loss of fluid back between the slide and the piston during operation. The slide has grooves 138 and 13s on its top providing communication with an inlet 14%, and similar grooves are provided on the bottom of the slide for providing communication with an outlet Mil.

The slides of FIGS. 12 and 13 are shown as slightly modified with a series of grooves arranged for strengthening the slide where high pressure is produced by the pump. The top includes a pair of H-shaped grooves 151 and 152 arranged to each side of the slide and a central single slot 153 provided down the middle. 0n the bottom side of the slide a pair of grooves 155 and 156 is arranged at one side of the slide and another pair of grooves 157 and 158 is provided at the opposite side. The lands between the grooves strengthen the slide so that there is a minimum of open space in the material providing strength.

The pump is constructed and shafts are operated conjointly so as to maintain each piston in contact with the slide and essentially in contact with the cylinder wall. The double piston pump therefor produces the equivalent of two strokes per revolution, and the four piston pump produces the equivalent of four strokes per revolution of each shaft.

While the invention has been illustrated by reference to specific embodiments, there is no intent to limit the spirit and scope of the invention, except as defined in the following claims.

I claim:

1. Fluid pumping apparatus comprising a housing having enclosed therein at least a pair of spaced apart cylin drical chambers with a rectangular cross-section passage therebetween, a shaft rotatably mounted in each chamber and said shafts being connected for conjoint and opposite rotation, an eccentric rigidly mounted on each shaft in each chamber and mounted 180 opposed to each other, a rotary piston mounted on each eccentric and in each chamber, each said piston being of a smaller diameter than its enclosing chamber and arranged for rotation on its eccentric so as to be in continuous essentially tangential contact with its cylinder wall, a reciprocable slide valve mounted in said passage between said chambers and arranged to be in continuous contact with both of said pistons, a fluid inlet in said housing communicating with one side of said slide valve, a fluid outlet in said housing communicating with the opposite side of said slide valve, said valve forming a continuous barrier between said in let and said outlet, said valve having a length substantially the same as said passage so as to close said inlet and said outlet from both said chambers when said valve is centered in said passage and to close one chamber when the other chamber is open to said inlet and said outlet whereby said chambers are completely separated, said valve having end walls arranged to close said passage when positioned therein, there being a depression on each side of said valve to provide communication between said chambers and said inlet and outlet, whereby rotation of said pistons reciprocally moves said valve to separately and alternately provide communication between said inlet and said outlet and each said chamber, and means for rotating said shafts.

2. Fluid pumping apparatus comprising a housing having at least a pair of spaced apart cylindrical chambers with a rectangular cross-section passage therebetween, a shaft rotatably mounted in each chamber and said shafts being connected for conjoint and opposite rotation, an eccentric rigidly mounted on each shaft in each chamber and mounted 180 opposed to each other, a rotary piston mounted on each eccentric and in each chamber, each said piston being of a smaller diameter than its enclosing chamber and arranged for rotation on its eccentric so as to be in continuous essentially tangential contact with its cylinder wall, a reciprocable slide valve mounted in said passage between said chambers and arranged to be in continuous contact with both of said pistons, a fiuid inlet in said housing communicating with one side of said slide valve, a fluid outlet in said housing communicating with the opposite side of said slide valve, said valve forming a continuous barrier between said inlet and said outlet, a set of ball bearings mounted between said valve and the wall of said passage on the inlet side thereof, said valve having a length substantially the same as said passage so as to close said inlet and said outlet from both said chambers when said valve is centered in said passage and to close one chamber when the other chamber is open to said inlet and said outlet whereby said chambers are completely separated, said valve having end walls arranged to close said passage when positioned therein, there being a depression on each side of said valve to provide communication between said chambers and said inlet and outlet, whereby rotation of said pistons reciprocally moves said Valve to separately and alternately provide communication between said inlet and said outlet and each said chamber, and means for rotating said shafts.

3. Fluid pumping apparatus comprising a housing having at least a pair of spaced apart cylindrical chambers with a rectangular cross-section passage therebetween, a

shaft rotatably mounted in each chamber and said shafts being connected for conjoint and opposite rotation, an eccentric rigidly mounted on each shaft in each chamber and mounted opposed to each other, a rotary piston mounted on each eccentric and in each chamber, each said piston being of a smaller diameter than its enclosing chamber and arranged for rotation on its eccentric so as to be in continuous essentially tangential contact with its cylinder wall, a horizontally disposed reciprocable slide valve mounted in said passage between said chambers and arranged to be in continuous contact with both of said pistons, a lower fiuid inlet in said housing communicating with the bottom side of said slide valve, a fluid outlet in said housing communicating with the opposite side of said slide valve, said valve forming a continuous barrier between said inlet and said outlet, bearing means mounted beneath said valve and on the Wall in said passage, said valve having a length substantially the same as said passage so as to close said inlet and said outlet from both said chambers when said valve is centered in said passage and to close one chamber when the other chamber is open to said inlet and said outlet whereby said chambers are completely separated, said valve having end walls arranged to close said passage when positioned therein, there being a depression on each side of said valve to provide communication between said chambers and said inlet and outlet, whereby rotation of said pistons reciprocally moves said valve to separately and alternately provide communi cation between said inlet and said outlet and each said chamber, and means for rotating said shafts.

4. Fluid pumping apparatus according to claim 3 in which each said piston is provided with a covering of a resilient plastic material and said slide valve is of a resilient plastic material, and said pistons are mounted so as to not slide on the wall of its cylinder.

References Cited in the file of this patent UNITED STATES PATENTS Switzerland Sept. 26, 1894 

1. FLUID PUMPING APPARATUS COMPRISING A HOUSING HAVING ENCLOSED THEREIN AT LEAST A PAIR OF SPACED APART CYLINDRICAL CHAMBERS WITH A RECTANGULAR CROSS-SECTION PASSAGE THEREBETWEEN, A SHAFT ROTATABLY MOUNTED IN EACH CHAMBER AND SAID SHAFTS BEING CONNECTED FOR CONJOINT AND OPPOSITE ROTATION, AN ECCENTRIC RIGIDLY MOUNTED ON EACH SHAFT IN EACH CHAMBER AND MOUNTED 180* OPPOSED TO EACH OTHER, A ROTARY PISTON MOUNTED ON EACH ECCENTRIC AND IN EACH CHAMBER, EACH SAID PISTON BEING OF A SMALLER DIAMETER THAN ITS ENCLOSING CHAMBER AND ARRANGED FOR ROTATION ON ITS ECCENTRIC SO AS TO BE IN CONTINOUS ESSENTIALLY TANGENTIAL CONTACT WITH ITS CYLINDER WALL, A RECIPROCABLE SLIDE VALVE MOUNTED IN SAID PASSAGE BETWEEN SAID CHAMBERS AND ARRANGED TO BE IN CONTINUOUS CONTACT WITH BOTH OF SAID PISTONS, A FLUID INLET IN SAID HOUSING COMMUNICATING WITH ONE SIDE OF SAID SLIDE VALVE, A FLUID OUTLET IN SAID HOUSING COMMUNICATING WITH THE OPPOSITE SIDE OF SAID SLIDE VALVE, SAID VALVE FORMING A CONTINUOUS BARRIER BETWEEN SAID INLET AND SAID OUTLET, SAID VALVE HAVING A LENGTH SUBSTANTIALLY THE SAME AS SAID PASSAGE SO AS TO CLOSE SAID INLET AND SAID OUTLET FROM BOTH SAID CHAMBERS WHEN SAID VALVE IS CENTERED IN SAID PASSAGE AND TO CLOSE ONE CHAMBER WHEN THE OTHER CHAMBER IS OPEN TO SAID INLET AND SAID OUTLET WHEREBY SAID CHAMBERS ARE COMPLETELY SEPARATED, SAID VALVE HAVING END WALLS ARRANGED TO CLOSE SAID PASSAGE WHEN POSITIONED THEREIN, THERE BEING A DEPRESSION ON EACH SIDE OF SAID VALVE TO PROVIDE COMMUNICATION BETWEEN SAID CHAMBERS AND SAID INLET AND OUTLET, WHEREBY ROTATION OF SAID PISTONS RECIPROCALLY MOVES SAID VALVE TO SEPARATELY AND ALTERNATELY PROVIDE COMMUNICATION BETWEEN SAID INLET AND SAID OUTLET AND EACH SAID CHAMBER, AND MEANS FOR ROTATING SAID SHAFTS. 